Prior to the coming of the Spaniards to this continent, many of the Indians of our Southwest constructed houses of mud. For the most part, their construction consisted of an outline of the walls with branches, cactus ribs, reeds, or the like, strung between corner posts and then covering the framework so constructed with mud on both sides. The resultant wall was usually about six or more inches in thickness and provided a house which, when roofed over, had remarkable air-conditioning properties and was weatherproof and fireproof.
When the Spanish came to this area, they modified this old type of structure by constructing adobe bricks, usually of approximately four inches in thickness by twelve inches in width and sixteen or eighteen inches in length. These bricks were thoroughly dried and then laid one upon another to form a wall, the adobe bricks being mortared together with mud. This type of structure was very common in the old Southwest and is still used to a greater extent than is usually realized, because it can be made of local materials by unskilled labor; is completely fireproof and weatherproof; and, in that climate, will stand for generations even without plastering. Such a building has great thermal insulation properties and is therefore very popular because it is cool throughout the summer and warm in winter. This type of construction has little earthquake strength and was therefore replaced in the earthquake areas by wood, or frame buildings which, in past years, were rather inexpensive but is now becoming quite expensive.
At the present time, due to the expense of the frame or reinforced brick construction, adobe buildings are attracting considerably more attention and many homes and public buildings are being constructed of adobe. This is particularly true when the building is only one story in height.
Recent developments have tended to increase the use of what is often called "poured mud" construction. This type of construction is more closely related to the pre-Spanish Indian type in which the adobe mud, instead of being cast into bricks and dried, is poured around an inexpensive reinforcing structure to form an integral reinforced wall. It is commonly known as a "poured adobe" wall and retains all the advantages of the old Indian plaster mud and the Spanish adobe brick of the past. It is virtually waterproof, has great heat and sound insulation properties, is fireproof, termite-proof and has high compression and shear strength. The reinforcing of the wall can render it quite resistant to earthquake destruction, depending upon the type of reinforcing utilized.
One of the recent developments in this field is in the use of an emulsified asphalt in the mud mix to render the walls made of this mix completely waterproof and very highly resistant to water errosion. Some work is being done at present on the use of other additives that would be cheaper or more efficient than emulsified asphalt and yet render the adobe material completely resistant to moisture, water errosion, abrasion, etc. Also, much work is being done toward the development of less expensive reinforcing materials.
Heretofore, the reinforced adobe walls have been reinforced by laying steel reinforcing rods horizontally between courses approximately two feet apart. The ends of the rods are encased in a concrete post poured later to make a unitary wall. Such construction is rather expensive, requires the use of reinforcing steel, and is not practical in under-developed countries or areas in our own country requiring low-cost or owner-built construction.
It has also been suggested that the use of a wire reinforcement, such as wire mesh, extending vertically in a poured wall is sufficient. Such construction does not have the integral strength against earthquake damage that comes from the use of reinforcing steel rods, the ends of which are embedded in concrete posts. It has also been suggested to use pre-formed parallel wire mesh which are tied together by some suitable means, such as welded or tied rods, and forming the wall around it or on it. Such construction is rather awkward to make and the reinforcement is in the way of construction.
The structure of my invention includes hanging a series of wire trusses on a wire stretched between corner posts of the wall, preferably a truss about every six to twelve inches along the length of the wall. Wire mesh, either of 1".times.1" or 1".times.2" size, is affixed to both sides of the wire truss, as by placing a short iron pin or nail between the apex of a truss and the wire mesh. Obviously, many different ways of affixing the wire mesh to the wire truss are available and could be used interchangeably. Rough door framing, window framing, and other wall apertures are hung on the wire truss and the wall will be constructed around them and the truss members within such a frame will be cut away after the wall is completed.
The wall can be constructed by using a form and pouring and compacting the adobe mud into it. In this type of construction it is usual to pour material for a depth of about a foot, or maybe two, and after the wall has dried sufficiently, remove the form to the adjacent location and proceed around the wall. By the time construction gets around to the section first poured, the wall is usually dry enough to place the form on top of the first course and pour a second, etc. Another type of construction is to form a very stiff mud and to plaster or press it through the wire mesh. In this form it is not necessary to completely fill the interior of the wall as the wire mesh will support a wall of proper mud consistency for a height of about a foot without slumping, then when the worker returns to the first course, it will have dried sufficiently to permit it to be used as a form to fill the interior space with mud to form a solid wall and then to plaster another foot or so of mud onto the form.
When the adobe wall is constructed, it is preferred to cap it either with a wooden beam or a bond beam of reinforced concrete. In this case, the top part of the wire truss will extend above the cap beam and is used to attach the roof truss to the reinforcing which extends from the foundation up through the wall. This forms an integral foundation wall roof structure which greatly resists earthquake damage and still retains all of the other advantages of adobe construction.